1. Field of the Invention
The present invention relates to continuous data protection, and more particularly, to continuously archiving data on a storage device within a pre-set time period.
2. Background Art
Currently, there are a number of conventional methods that relate to organization of data archiving. One of these methods is a backup of the entire hard drive, which typically involves copying of the hard drive contents onto some other medium (such as, for example, another hard disk drive, a DVD ROM, a DVD RAM, a flash disk, etc.). The primary disadvantage of such a method is a need to backup what can be a very large amount of data, which, on the one hand, results in a relatively lengthy process of archiving, and, on the other hand, frequently requires relatively large available space for the archived data. This ultimately results in a relatively high cost of archiving per unit of archived data.
Another approach is often referred to as “incremental backup,” which generally decreases the amount of space required for the archiving. With the incremental backup, typically, the contents of the hard disk drive are archived, or stored somewhere once. After that, only the data that has been changed, or added, since the previous backup, or since the pervious incremental backup, is actually archived. Recovery of the data from the archive typically involves merging of the original backup and the various incremental backups.
For conventional backups it is possible to restore data to the point at which the backup was taken. In case of a system failure, the data can be restored from the last incremental backup. In this case, data from the time of this incremental backup creation up to the time of a system failure will be lost.
On the other hand, continuous data protection is different from traditional backups. With continuous data protection, an initial backup can be created as in the case of a traditional backup, but the new data (which is written on the storage device) is backed up in the incremental backup in parallel to writing on the storage device. In other words, the new data is backing up to the incremental backup during the process of the new data being written to the storage device.
In some cases a full back up is not needed. Instead, only the previous versions of files or parts thereof (i.e., data-sets), which are rewritten as a result of write file requests, can be saved (i.e., backed up). However, viewing and accessing a number of previous versions of files can be a difficult and time consuming process.
Accordingly, there is a need in the art for an effective and efficient method of continuous protection of files that provides an easy and convenient way of viewing previous versions of data contained on data storage a while ago. The viewing of the previous versions of data should be done with minimal time and effort, so the data backup process allows a computer system to remain online (so called online backup, instead of a off-line backup, where the system must be stopped to end the backup process), with a possibility to restore data from the backup at the time of the system failure up to any pre-selected points of restoration.